Perpendicular magnetic recording has been developed in part to achieve higher recording density than is realized with longitudinal recording devices. A PMR write head typically has a main pole layer with a small surface area (pole tip) at an ABS, and coils that conduct a current and generate a magnetic flux in the main pole such that the magnetic flux exits through the pole tip and enters a magnetic medium (disk) adjacent to the ABS. Magnetic flux is used to write a selected number of bits in the magnetic medium and typically returns to the main pole (MP) through two pathways including a trailing loop and a leading loop. The trailing loop is comprised a trailing shield structure with a front side at the ABS, an uppermost (PP3) trailing shield that arches over the driving coil and connects with a top yoke (TY). The TY adjoins a top surface of the MP above a back gap connection (BGC). The trailing loop is also known as the top driving loop and delivers magnetic flux to the MP tip to write positive and negative field into magnetic media. The leading loop has a leading shield with a side at the ABS and in some schemes is connected to a return path (RTP) having a front side recessed from the ABS. The RTP extends back to the BGC and enables magnetic flux in the leading loop pathway to return from the leading shield at the ABS and through the BGC to the MP for faster saturation speed, better adjacent track interference (ATI) and enhanced wide area track erasure (WATE) potential.
Dual write shield (DWS) designs that feature complete leading and trailing loops were invented for adjacent track erasure (ATE) improvement by reducing stray field in side shields and in the leading shield and trailing shields. Accordingly, a PMR head has a great advantage over LMR in providing higher write field, better read back signal, and potentially much higher areal density. With the growing demand for cloud storage and cloud-based network computing, high and ultra high data rate recording becomes important for high-end disk drive applications.
To achieve areal density in a HDD beyond 2 TBPP for conventional PMR in near line applications, OD high data rate (HDR) performance up to 3.4 gigabytes per second (Gbps) or 1.7 gigahertz (GHz) is essential and critical. A one turn coil design (1+1T) has demonstrated better HDR performance than a two turn coil design (1+1+2T or 2+2T) because of less electrical inductance and more compact magnetic loop with shorter yoke length (YL). Magneto-motive force (MMF) of a one turn coil design is half that of a 2+2T design. Under direct current (DC) or low frequency alternating current (AC) applications, a one turn coil writer requires two times the current of a two turn coil writer to drive a head to the same magnetic field level. However, under high frequency for HDR applications, the 1+1T design has demonstrated an advantage in reaching the same magnetic field level with 1.2-1.5 times the current of a two turn coil design for 1.75 TBPP application with a data rate up to 3.1 Gbps (1.55 GHz). Thus, the 1+1T design, which can operate at less than 1.5× the Iw(0-peak) current of 1+1+2T or 2+2T designs offers less driving to the write shield and better WATE capability that is critical for near line applications. In order to meet the requirements of 2TBPP applications, a faster 1+1T writer that can pick lower Iw0-pk at OD operation than existing 1.75 TBPP 1+1T designs is needed.